Methods and apparatus for butt welding wires and the article produced therefrom



May 21, 1968 w. J. DRAVING 3, ,7

METHODS AND APPARATUS FOR BUTT WELDING WIRES AND THE ARTICLE PRODUCEDTHEREFROM Original Filed Oct. 28, 1964 5 Sheets-Sheet 1 Fl .7. FIG 6. 93/ WELDING.

. Z INVENTORZ WALTER J. DRAVING May 21, 1968 w. J. DRAVING 3,

METHODS AND APPARATUS FOR BUTT WELDING WIRES AND THE ARTICLE PRODUCEDTHEREFROM Original Filed Oct. 28, 1964 f5 Sheets-Sheet 2 FIG.IO FIG! I.

/7 a I 2 2 m W2 1 g g V (5 Q 5% /7 FIGZL f 2/62 22 9: 1 I I INVENTOR QWALTER J. DRAVING 1 BY 2/6 ,Q/dg 22P+ ATTYS- May 21, 1968 w. .1. DRAVING3,384,7

METHODS AND APPARATUS FOR BUTT WELDING WIRES AND THE ARTICLE PRODUCEDTHEREFRO Original Filed Oct. 28, 1964 .5 Sheets-Sheet 5 2 r/ H624. 326 vI ATTYS.

% J INVENTOR: 2 WALTER J. DRAVING United States Patent U 3 384,731METHODS AND APPARATUS FOR BUTT WELD- ING WIRES AND THE ARTECLE PRODUCEDTHEREFROM Walter J. Draving, Willow Grove, Pan, assignor to PhiladelphiaMetal Stamping Company, ind, Philadelphia, Pa., a corporation ofPennsylvania Continuation-impart of application Ser. No. 315,884, Get.14, 1%3, and a continuation of application Ser. No. 407,204, Oct. 28,1964. This application May 18, 1967, Ser. No. 639,588

24 Claims. (Cl. 219-57) ABSTRACT ()F THE DlSiILGSURlE This patentdiscloses a method of and apparatus for welding together smallworkpieces including one of the novel articles as a product of themethod. The method discloses welding together such workpieces byutilizing novel apparatus including a pair of fixedly spaced electrodedieholders, one of the die-holders serving to rigidly clamp one of theworkpieces thereto while the other of the die holders having means forloosely clamping the other of the workpieces. After the workpieces arethus positioned, a potential is applied between the die-holders and theloosely clamped workpiece is moved into contact with the other workpiecethereby discharging the potential through the workpieces causing a Weldto be effected.

This application is a continuation-in-part of the copending application,S.N. 315,884, filed October 14, 1963, now abandoned, and a continuationof co-pending application Ser. No. 407,204, also now abandoned.

The present invention relates to methods and apparatus for welding wiresor the like and more particularly relates to methods and apparatus forelectrical-resistance welding and the resultant products therefrom.

Welding techniques and apparatus currently available on the marketpertaining to welding of small diameter wires and the like have verycommon shortcomings. They are bulky, relatively expensive, and despitetheir excellence of engineering design are only capable of achievinggood welds approximately 50% of the time. Further, when end-to-endwelding two wires of differing diameters and/ or having the same ordiffering physical characteristics, the percentage of good welds fromany of these machines is decreased.

The welding methods presently employed may be divided into three generalclassifications, Butt Welding, Flash Welding, and Percussion Welding. Inthe butt welding process the pieces to be welded together are clamped,brought together and a high pressure between 2500 and 8000 p.s.i. isapplied and thereafter a heavy current is passed through the two piecesthereby effecting a weld at the junction of the pieces. It is obvious,with soft Wires or wires of relatively minor diameters, alignment of thepieces in addition to extreme pressures applied is extremely ditficultand oftentimes an upsetting of the joint occurs. Further, if twodissimilar metals are to be welded, the metal projecting from theelectrode die-holders must be in proportion to the specific resistanceof the materials to be welded which, of course, adds to the diflicultyin alignment and applying the high pressures to effect a good weld.These comments also apply where material of differing cross sections arebutt welded.

In flash welding, the parts are first clamped, then brought together invery light contact and then a high 3,384,731 Patented May 21, 1968voltage starts a flashing action between the two surfaces as the partsadvance slowly and the forging temperature is attained. The weld is onlycompleted thereafter by the application of suflicient forging pressure,which may range from 5000 to 25,000 p.s.i. Further, although certainnonferrous metals are capable of flash welding, alloys containing highpercentages of lead, Zinc, tin, and copper are not recommended for usein this process. As in butt welding, the use of flash welding techniquesin welding small diameter workpieces or wires is inadequate because ofthe high pressures necessary to effect a good weld.

In percussion Welding the pieces are clamped approximately of an inchapart and a high voltage is applied causing intense arcing over thesurfaces bringing them to a high temperature. The are is extinguished bythe percussion blow of the two parts coming together with sufficientforce to form a weld. As before, the equipment utilized for percussionwelding is expensive since it isextremely rugged and must be providedwith accurate holding fixtures and with elaborate electrical timingdevices and large transformer capacities.

As may be seen from the foregoing, there are several major disadvantagesinherent in the present day apparatus and techniques of welding smalldiameter workpieces or wires. It is obvious, that wires havingdissimilar bending properties will experience alignment diflicu-ltiesupon the application of relatively large amounts of force, which forceis necessary in all three of the foregoing conventional techniques.Further, heretofore it has been felt necessary that both pieces to bewelded must be securely clamped because of the necessity of decreasingthe resistance of the die-holder to the workpieces at the point ofclamping thereby preventing a weld from being effected at those pointsto their respective workpiece. In addition, when clamping and bringingthe two pieces together via displacement of the clamping die-holders,the workpieces have to have an inherent physical size and structuralstrength suflicient to withstand and overcome the inertia of the clampsupon the Welding pressure being applied. Unfortunately, small wires donot have these structural qualifications.

In view of the above, it is a principal object of the present inventionto provide welding methods and apparatus therefore, which apparatus andmethods will perrnit of welding together two or more small work piecesin a simple and economical manner.

Another object of the present invention is to provide novel electrodedie-holders which permit relative movement of one workpiece with respectto the other without the necessity of moving the electrode die-holders.

Another object of the present invention is to provide a method ofwelding or a welding technique which permits a good weld between asingle wire and a multiplicity of wires each having a smaller diameterthan the single wire.

Another object of the present invention is to provide apparatus whichpermits of welding a multiplicity of workpieces to a workpiece having alarger diameter, in one operation.

Still another object of the present invention is to provide a novelmethod and apparatus of welding workpieces having a larger diameter.

Another object of the present invention is to provide novel apparatusand a novel method of welding which permits welds to be made tomicro-miniature electronic parts.

Still another object of the present invention is to provide apparatuswhich is easily adjustable and permits easy axial alignment of wires inthe electrode die-holders.

Another object of the present invention is to provide apparatus whichwill automatically, upon engagement with the wires, cause straighteningthereof so as to insure automatic alignment between the two pieces to bewelded.

Other objects and a fuller understanding of the invention may be had byreferring to .the following specification and claims taken inconjunction with the accompanying drawings in which:

FIG. 1 is a fragmentary perspective view showing schematically apparatusconstructed in accordance with the present invention;

FIG. 2 is an enlarged fragmentary perspective view of a portion of theapparatus illustrated in FIG. 1;

FIG. 3 is an enlarged plan view of a portion of the apparatusillustrated in FIG. 2;

FIG. 4 is a fragmentary sectional view taken along line 4-4 of FIG. 3;

FIG. 5 is an enlarged fragmentary sectional view taken along line 5-5 ofFIG. 3;

FIG. 6 is an enlarged sectional view of a portion of the apparatusillustrated in FIG. 5;

FIG. 7 is an enlarged fragmentary sectional view, similar to FIG. *6,and illustrating another portion of the apparatus shown in FIG. 3;

FIG. 8 is an enlarged plan view of a portion of the apparatus shown inFIG. 3 and in a different position so as to illustrate more accuratelythe placement of work pieces relative thereto;

FIG. 9 is a fragmentary plan view illustrating schematically, in part,the operation of apparatus illustrated in FIGS. 1-8;

FIG. 9a is a fragmentary schematic illustration of the movement of workpieces to effect a weld in accordance with the invention;

FIGS. 10 and 11 illustrate different embodiments of a portion of theapparatus constructed in accordance with the present invention;

FIG. 12 is an enlarged plan view similar to that illustrated in FIG. 8but showing the position of a multiplicity of work pieces relative toanother work piece to which the former are to be welded.

FIG. 13 is an enlarged fragmentary perspective view of a portion of theapparatus illustrated in FIG. 12 and taken along line 1313;

FIG. 14 is an enlarged fragmentary perspective view of a portion of theapparatus illustrated in FIG. 12 and taken along line 14-14 of FIG .12;

FIGS. 15 and 16 are enlarged fragmentary perspective views similar tothat of FIGS. 13 and 14 and showing another embodiment of that portionof the apparatus, constructed in accordance with the present invention;

FIG. 17 is plan view of another embodiment of the invention;

FIG. 18 is a fragmentary sectional view taken along line 18--18 of FIG.17;

FIG. 19 is an enlarged fragmentary sectional view of portion of theapparatus illustrated in FIG. 17 and taken along line 1919;

FIG. 20 is a fragmentary enlarged view of work pieces joined by a weldin accordance with the present invention and the apparatus heretoforeillustrated;

FIG. 21 is an enlarged fragmentary view of a multiplicity of work pieceswelded end to end in accordance with the apparatus and method of thepresent invention;

FIG. 22 is an enlarged fragmentary sectional view taken along line 22-22of FIG. 21;

FIG. 23 is a fragmentary plan view of another embodiment of theinvention;

FIG. 24 is a profile of the apparatus illustrated in FIG. 23;

FIG. 25 is a fragmentary sectional view taken along line 25-25 of FIG.24;

FIG. 26 is a fragmentary enlarged sectional view of a portion of theapparatus illustrated in FIG. 24 and wherein one of the work pieces isan electronic part;

FIG. 27 is a sectional view taken along line 27-27 of FIG. 26; and

FIG. 28 is a schematic wiring diagram of a typical welding unit utilizedin conjunction with apparatus constructed in accordance with the presentinvention.

Referring now to the drawings, and especially FIG. 1 thereof, asimplified schematic representation of welding apparatus 10 mounted on astand or work bench 11 and having an adjustable magnification viewingpiece 12, is illustrated therein. As illustrated in FIGS. 1 and 2, thewelding apparatus 10 comprises a pair of electrode dieholders 13 and 14mounted in an insulated block 15 secured to the work table 11. Clamps 23and 24, con nected to the welding apparatus 10, operate to clamp workpieces, in the present instance wires 16 and 17, to the electrodedie-holders 13 and 14 respectively. As shown in FIG. 9, a welding pack50 is connected to the electrode die-holders 13 and 14 and put intooperation via a foot switch 18.

In accordance with the method of the present invention, at least one ofthe work pieces is clamped to its associated electrode die-holder whilethe other work piece is aligned with the first work piece and looselyclamped to the other electrode die-holder. Upon applying a potentialbetween the electrodes, the loosely engaged work piece is moved relativeto the fixedly clamped work piece until the work pieces contact oneanother thereby discharging the potential through the work pieces andcausing them to weld together at their junction.

Because the techniques and apparatus for welding relatively smalldiameter wires or work pieces differ, in accordance with the diameter ofthe Work piece, the physical and/or chemical characteristics of the workpiece, and whether or not it is desired to retain approximately the sameoverall dimensions of the work piece, the remaining portion of thespecification is conveniently divided into two parts; the first partdealing with A Method and Apparatus for Welding Small Diameter WorkPieces, and the second section dealing with A Method and Apparatus forWelding Large Diameter Work pieces.

A METHOD AND APPARATUS FOR WELDING SMALL DIAMETER WORK PIECES As themethod and apparatus disclosed hereinafter is also applicable to certaindiameter work pieces which may be classified in the second section ofthis specification, it should be recognized from the outset that themethod and apparatus are not capable of a fixed boundary with respect tothe diameter of the work pieces and that some overlapping is possible.In this section, small diameter wires will be referred to as includingwires from below .0001 of an inch to approximately .125 of an inch.

Referring now to the drawings, it is noted that the electrodedie-holders 13 and 14 are L-shaped each having an upstanding leg 19 and20 respectively and spaced from each other so as to receive therebetweenan insulator 21. At the extended terminus of the legs, work piecereceiving means 30 are provided to receive, in the present instance, thesmall diameter wires 16 and 17, and to permit axial alignment of thewires when inserted therein.

In the illustrated instance the receiving means 30, associated with eachof the legs 19 and 20 of the electrode die-holders 13 and 14, comprisesa pedestal or raised portion 31 having a groove 32 and a rearwardterminal recession 33, the purpose of which will more fully be ascribedhereinafter.

Positioned above each of the wire receiving means 30 are the clamps 23and 24, at least one of which acts upon its associated work piece orwire to fixedly engage the wire in its groove with a small portionprojecting into the space defined between the legs 19 and 20. To thisend,

and as best illustrated in FIG. 5, each of the clamps has a horizontalextension 25a having a handle 25b at one end and pivotably secured toits associated leg by adjustment means at the other end. In the presentinstance the adjustment means comprises a bolt 26 having a shoulder 27permitting rotatable movement of the clamp, and permitting verticaladjustment thereof due to the biasing effect of a spring 28. In thismanner one clamp, in the present instance clamp 23, may firmly engagethe wire in the groove 32 while the other clamp, in the present instanceclamp 24, may loosely engage the other wire 17. To insure maximumflexibility of the apparatus, as different diameter wires may beinserted into the groove associated with the wire receiving means ofeither leg 19 or 20, the clamps should be adjustable in order to raiseand lower the extension 250 so as to insure proper seating of the wirein its associated groove.

As it is desirable that wires placed in the grooves are easilyalignable, and as in many instances the wires inserted in the wirereceiving means may be bent, the clamps are provided with means tostraighten the wires. To this end, and in accordance with a feature ofthe invention, the portion of each clamp which engages with the wire tocause it to be placed in a groove is provided with a portion 29,parallel to the pedestal 31 (see FIG. and which cooperates with therecess or groove 33 to permit engagement of the surface 29 against abent wire in a Wiping action which moves the wire into the groove 32thereby straightening it. Such an action is illustrated in FIG. 8.

It is important to note the relative position of the clamps 23 and 24with respect to the wires 16 and 17. As previously set forth and as seenin FIG. 6, one of the clamps, in the present instance clamp 23, isadjusted so that the surface 29 presses the wire 16 firmly into thegroove 32 while the other clamp, in the present instance clamp 24, isadjusted so that the surface 29 just engages the upper portion of thework piece or wire 17 in its associated groove 32. This of coursepermits movement of the wire 17 relative to the wire 16 in a mannerwhich will be more fully described hereinafter. Although the shape ofthe groove 32 as illustrated in FIGS. 6 and 7 is U shaped, a V-shapedgroove 132 such as illustrated in FIG. 10 or a rectangular shaped groove232. as well as any groove shape which permits contact between the wireand the electrode may also be used.

As it is desirable to achieve perfect alignment of the goroves, it maybe desirable to provide means to move the electrode die-holders relativeto each other so that the grooves may be aligned in both the horizontaland vertical planes. To this end, apparatus such as previously describedis illustrated in FIGS. 17 and 18 wherein a pair of L-shaped electrodedie-holders 113 and 114 having upstanding legs 11 and 120 respectivelyare spaced from one another and provided with horizontal adjust mentmeans 121 and vertical adjustment means 122. As it is necessary toadjust only one of the electrode dieholders with respect to the other ineither plane, the horizontal plane adjustment means, in the presentinstance, is located on the die-holder 113 while the vertical planeadjustment means 122 is located on the die-holder 114. The horizontaladjustment means in the present instance comprises a pair of presettablescrews 121a and 121b which bear against the die-holder 113 permitting itto be adjusted relative to a hold-down screw 130.

Although the clamp as heretofore described is preferable in combinationwith the wire receiving means, where the wires to be welded haveconsistent linearity in the longitudinal direction, the groove forreceiving the wire 116 or 117 may comprise an aperture 123 with an outwardly directed conical countersink 124- which permits easy alignment ofthe wires in the grooves. In this instance, the means to clamp the wirewith respect to the groove may take the form of a simple set screw 125such as illustrated in FIG. 19. Of course as before, one of the wires,for example the wire 116 is rigidly clamped with respect to the leg 119while the other wire 117 is loosely clamped by its set screw so that thewire 117 may be brought into contact with the other wire 116.

In practice, the welding of wires having the same or differing physicalcharacteristics and the same or differing diameters within the range ofsmall diameter wires as heretofore described, requires a relativelylight current discharge to effect a good weld. To this end, a verysimple welding pack may be provided so as to permit selective adjustmentof the current discharge. In the present instance, the welding apparatusis preferably of the capacitive discharge type although pulse typeelectromagnetic discharge welding machines or magneto type pulse systemcould be used with appropriate timing mechanism to insure placement ofthe potential on the wires prior to bringing the wires together.However, because of the relative simplicity of capacitive dischargewelding apparatus, it is to be desired. In FIG. 28, such apparatus isillustrated and comprises an isolation transformer 51 which inductivelycouples AC. to its secondary, and an auto-transformer 52 which permitsadjustment of the AC. voltage to a rectifier 53. The rectifier permits aDC. potential to be applied to switching means, in the present instanceas illustrated a double pole single throw switch 54, one pole 54a ofwhich is normally closed, the other pole 54b of which is normally open.The normally closed portion of the switch 54 connects the rectifier 53to a bank of capacitors 55 which includes plug-in means, such asillustrated at 56 and 57 for adding additional capacitance in parallelwith the capacitors 55 across the power supply. A volt meter 58 isconnected in parallel with the capacitors so as to afford a convenientmethod of reading the voltage being applied to the pole 54b of theswitch 54. The normally open portion of the switch 54b is electricallyconnected through a lead 59 to an electrode dieholder and mechanicallyconnected to the foot switch 18.

As may be noted from the simple schematic, upon the normally open pole54b of the switch 54 being depressed, so as to cause continuity to bemade between the capacitors and one of the electrode die-holders, theother pole 54a is opened, thereby disconnecting the rectifier 53 fromthe capacitive bank 55. As the other of the electrode die-holders isconnected to ground, or common with the grounded side of the capacitivebank, upon the switch 54 being actuated a potential is placed upon oneof the wires being held by the electrode die-holder and the circuit iscompleted for discharge of the capacitors upon the wires meeting. Itshould be noted that the switch means may take many forms, for example,an electronic switch or relay type switch.

The method of welding small diameter wires, specific examples of whichwill be set forth hereinafter, is illustratively depicted in FIG. 9awherein a small diameter wire 16a is assumed to be fixed in one of itsdie-holders 13 by its associated clamp while the other wire 17a isassumed to be loosely clamped in its die-holder such as the die-holder14 illustrated in FIG. 9. Thereafter the foot switch 18 actuates theswitch 54'to apply the charge on the bank of capacitors 55 (see FIG. 28)to the wire 17a thus creating a potential difference between the wire17a and the wire 16a. The wire 17a is then moved rapidly towards thewire 16a and upon contact the capacitor bank is discharged through thewires causing the wires to form molten bulbs 16b and 17b respectively asshown in FIG. 9a. The Wire 1711 is thereupon disengaged and moved to theright. The foot switch is released and the capacitors once again arepermitted to charge. Once again the foot switch 18 is depressed and thecapacitive charge of the capacitors 55 is placed on the wire 17a.Thereafter the wire 17a is brought towards the wire 16a and permitted tobutt thereagainst. Upon the wire 17a striking the wire 16a thecapacitors are once again discharged. This time upon removal of the wire17a or withdrawal from the other wire 16a small tits appear on the endsof the bulb as if a partial weld had occurred and in the molten stagewas pulled apart. Once again the footswitch is released and thecapacitor bank is permitted to recharge. Thereafter the charge isre-applied. and the wire 17a is once again brought against the wire 16a,and a weld is effected. Although the final weld, such as illustrated inan exaggerated fashion in FIG. 20, would appear to have to have abulging at the joint, for some reason which is not entirely clear themetal appears to flow at the junction and form a cross sectionsubstantially identical with the cross section of the two Wires. Forexample, a pair of wires having diameters of .020 of an inch, welded inthis manner, is guaranteed in production Welding, to fit through a holehaving a diameter of .021 of an inch.

From the above discussion of the method of welding small diameter wires,it is evident that this method is particularly conductive to theformation of welds wherein it is desired to maintain rigid control bothas to the size of the weld at its junction, and the relative length ofthe wires. The reason for this is that relatively little or no metal islost in the welding process. It further should be noted that the wiresto be welded together should not have extremely differing diameters as,it has been found, that this will prevent the formation of adequatewelds. Thus while it is a simple matter to weld, for example, a .002inch work piece to a .005 inch work piece, some dilficulty may beencountered in attempting to weld, in the above manner, a .002 inch workpiece to a .010 inch work piece.

As a practical matter, when welding two or more wires end to end, it ispreferable that the stiffer of the two wires be the loosely engaged wirewhile the wire having the least bend resistance be fixedly engaged inthe clamp.

In accordance with the method of the present invention, a plurality ofwires may be welded to a single wire end to end with apparatus similarto that disclosed in FIGS. 1-11 and as heretofore described. Such anembodiment, is illustrated in FIG. 12 wherein a pair of electrodedie-holders 213 and 214 each have a clamp, 223 and 224 respectively,positioned relative thereto to receive work pieces. In the instance ofthe clamp 223 and electrode die-holder 213, a plurality of wires 216 isfixedly engaged therebetwecn, while a single wire 217 of slightly largerdiameter to which the wires 216 are to be welded is, in a manner such asheretofore described, loosely engaged with respect to the die-holder 214by its clamp 224. FIG. 13 illustrates two wires 216a and 2161)respectively being fixedly engaged by the clamp 223 against theelectrode die-holder 213 while FIG. 14 illustrates a view of the same asit would appear upon engagement of the wire 217 against the wires 216aand 21Gb.

FIGS. 15 and 16 are illustrative of a three wire to one wire weld, thethree wires once again being fixedly clamped while the larger wire isloosely clamped and brought into engagement, end to end, for Weldingthereof. As may be noted in FIGS. 15 and 16, the plurality of wires hasbeen designated 216e, d, and e respectively while the larger diameterwire has been given the designation 217a.

Typical examples of wires welded in accordance with the above method andon apparatus as above described are given in the accompanying table andshould be considered merely illustrative of wires welded in this manner.It should be noted that the ranges of capacitance and voltage given inthe accompanying table may be varied considerably and still obtain agood weld by utilizing the method and apparatus as heretofore described.For example, variations in the particular alloy or alloying percentageor diametrical difference of small amounts may require slightdifferences in a voltage and/or capacitance in order that the best weldmay be obtained. Thus the table set forth below will give one practicingthe present invention a reasonable starting place.

Materials Diameter (inches) corres. Voltage, Capaci- Metal-to-Metal to 1and 2 in volts tanee,

Materials Col. pfd. 1 2

Copper Stnnliess .0015 006-. 007 20-25 300-400 tee .Do do .0015 003-.004 30-40 50-100 Beryllium Stainless 005 005 20-25 300-400 Copper. Steelor Copper. Carbon Steel. Stainless 003 002 20-25 300-400 iteel or opperor Beryllium Copper.

A METHOD AND APPARATUS FOR WELDING LARGER DIAMETER WORKPIECES Certain ofthe method and apparatus disclosed hereinafter is applicable to certaindiameter workpieces or wire which also may be classified in the firstsection of this specification. Therefore, it should be recognized at theoutset that the method of welding larger diameter wires is not capableof an absolute or fixed boundary with respect to the diameter or otherphysical characteristics of the workpieces and that some overlapping ispossible. In this section, larger diameter workpieces will be referredto as including wires or the like having diameters approximately .003 ofan inch to and in excess or .250 of an inch.

The method of welding larger diameter wires, as set forth hereinafter,permits the welding together of workpieces having greatly differingdiameters while creating some flash and therefore loss of metal when theworkpieces are joined. Thus utilizing the apparatus and/ or the methodas hereinafter set forth permits the welding of wires or the like toworkpieces having substantially larger surface areas, which surfaceareas may have diameters greater than /2 inch, for example a disk.

Referring now to the drawings, although apparatus as heretoforedescribed is equally applicable for use in welding workpieces havinglarger diameters, the apparatus illustrated in FIGS. 23-25 is to bepreferred. As illustrated in FIGS. 23 and 24, the welding apparatus 300,illustrated therein, comprises a pair of electrode dieholders 213' and214' each having an upstanding leg 219 and 220 respectively. At theextended terminus of the legs, workpiece receiving means are provided,in the present instance to receive larger diameter wires such as thewires 316 and 317, and to permit axial alignment of the wires in end toend relation when inserted therein. As heretofore described, theworkpiece receiving means comprises a pedestal or raised portion 231(see FIG. 25) having a groove 232 for receiving the wire therein.

As noted in FIG. 25, a clamp 224 serves to loosely engage the wire 317against the leg 220 of the die-holder 214. Similar to that heretoforedescribed, the clamp 224 comprises a horizontal extension 225a having ahandle 225i; at one end and pivotably secured to the leg 220 byadjustment means at the other end. In the present instance theadjustment means comprise a bolt 226 which permits rotatable movement ofthe clamp while simultaneously permitting vertical adjustment thereofdue to the biasing effect of a spring or the like (not shown).

For reasons which will become evident hereinafter, a clamp 240 serves tofixedly engage the wire 316 to the leg 219 of the die-holder 213'. Asbest illustrated in FIGS. 24 and 25, the clamp 240 comprises a yoke 241having a pair of upstanding legs 242 and 243 respectively biasedupwardly by a pair of springs 244 and 245, which springs support at oneend a clamping bar 246 and rest at their lower end on either side of thepedestal 231. Securing means 247 and 243 connect the terminal ends ofthe yoke 241 to the clamping bar 246 and thereby fix the distancebetween the upward terminus of the pedestal 231 and the lower portion ofthe clamping bar 246. In order to fixedly engage the wire 316 in itsgroove 232 and against the clamping bar 246 of the clamp 240, it is onlynecessary to depress a foot pedal 218 which through a stem 249 of theyoke 241, downwardly biases the yoke thereby causing the clamping bar246 to firmly engage the wire 316. It should be noted, that the footpedal 218 may be also used to cause actuation of the welding pack by aswitch 254, which may be similar to the switch 54 as previouslydescribed with reference to FIG. 28.

When welding wires in accordance with the method of the presentinvention, it is preferred that at least one of the wires such as thewire 317 have a pointed terminus which will contact the other wire whenthe one wire is moved relative to the other. Such a pointed terminus isshown at 317a, which point was made by a simple finger The welding ofmicrominiature or larger electronic elements such as diodes, transistorleads, capacitor leads, disks, or the like, may be accomplished byeither the small diameter work piece method or the larger diameter workpiece method whichever is applicable under existing circumstances.However, as the relative diameters of the elements may varyconsiderably, the larger diameter method is more desirable.

An example of such a welding technique is shown in the greatlyexaggerated view in FIG. 27, wherein a diode 275 having a Wire or stem276 is positioned for being welded to a lead wire 277. In theillustrated instance it is preferable to fixedly engage the stem 276 ofthe diode 275 and move the lead wire relative thereto. Assuming nailclipper. that the larger wire method is to be used, the diode isFurther, and as stated before, although a capacitive rigidly clamped,the wire 277, which is provided with discharge welding machine isdesirable and preferable a pointed terminus 278, is loosely engaged inthe other in the present application, a magneto-type dischargesysdie-holder and then a charge or potential is applied betem or otherelectro-magnetic discharge system which tween the stern 276 and the wire277 in a manner as gives a high pulse rate so as to approach D.C. alsocould heretofore described. The wire is then rapidly propelled beequally applicable for use in accordance with the towards the stem 276and the charge is then dissipated present invention. to ground throughthe junction of the wire 277 and the A method of Welding larger diameterworkpieces, spestem 276 thereby effecting a weld.

cific examples of which will be set forth hereinafter, Typical examplesof wires welded in accordance with requires, that one of the workpiecessuch as the wire 316 the above method and/or apparatus asabove-described be fixedly clamped in its electrode die-holder 213,while are given in the accompanying table and should be conthe otherworkpiece or wire be loosely clamped in its sidered merely illustrativeof wires welded in this manelectrode die-holder 214'. Further, it isdesirable that ner. It should be noted that the ranges of capacitanceone of the workpieces, if it is a wire, have a pointed terand voltagegiven in the accompanying table may be minus such as the terminus 317aon the wire 317. Thus, varied considerably and still obtain a good weldby the foot pedal 218 causes the wire 316 to be fixed relative utilizingthe method and apparatus as heretofore deto the die-holder 213' andsimultaneously actuation of scribed. For example, variations in theparticular alloy the welding pack occurs which causes a potential to beor alloying percentage or diametrical diiference of small placed on thewire 317 relative to the wire 316. The wire amounts may require slightdifferences in a voltage and/ 317 is then rapidly propelled towards theother fixed wire or capacitance in order that the best weld may be ob-316 and the potential is discharged to ground in a mantained. Thus thetable set fourth below will give one ner such as heretofore described.Unlike the method of practicing the present invention a reasonablestarting welding small diameter workpieces, this process requires place.

Materials Diameterfinches) Voltage, Capacitance,

Metal-to-Metal corres. to 1 and 2 in volts aid.

Materials 001. 1 2

Nichi'ome Steel Nsighrome .020 .030 40-30 5,00020,000 0 .020 20-3018,000-22,000 020-. 080 30-00 8, 000-12, 000 30 .045 9,000 020-. 08070-100 8, 000-12, 000 0 .045 50 0 00 only a single movement of theworkpiece relative to the other workpiece.

In practice, a common method of causing the wire 317 to be rapidlypropelled against the exposed terminal end of the wire 316 is to strikethe other terminal end 317b of the wire 317 with something hard.Although the blow is a relatively light one, it is sufiicient to causethe wire to be propelled with the necessary speed to strike the otherwire 316. Because of the extremely short distances involved, suffice tosay that the blow is easily produced by cooking the hand an inch or soaway from the terminal end 3171) of the wire and striking that end ofthe wire in a rapid manner.

In order that during quantity production of welds a uniform velocity maybe attained on the wire 317, automatic striking mechanism 260 may beprovided such as that illustrated in FIGS. 23 and 24. In the presentinstance the automatic striking mechanism comprises a spring 261positioned rearwardly of the terminus 3171) of the wire 317 and anchoredat a pivot 259. The spring 261 is held in a cocked position by a latch262 having a pivot at 263, and a latch release 264. Upon depression ofthe latch release 264 about the pivot 263, the latch 262 is elevated tothe dotted line position (see FIG. 24) and the spring 261 moves to theleft or clockwise about its pivot 259 thereby propelling the wire 317against the wire 316 whereby a weld is effected.

Thus novel welding apparatus and a novel method of welding are providedwhereby one workpiece is held rigidly fixed relative to the otherworkpiece and the movable workpiece is brought into contact after acharge has been applied thereto thus creating a weld. As may be notedfrom the drawings, and in accordance with the method as heretofore setforth, a simple but novel and efficient apparatus and method areprovided for effecting welds on relatively small diameter workpieces.

Although the invention has been described with a certain degree ofparticularity, it is understood that the present disclosure has beenmade only by way of example and that numerous changes in the details ofconstruction, method of operation, and the combination and arrangementof parts may be made without departing from the spirit and the scope ofthe invention as hereinafter claimed.

What is claimed is:

1. A method of Welding together at least two small workpieces in awelding machine having a pair of fixedspaced electrode dieholders;comprising the steps of clamping one of said workpieces to one of saidelectrodes, loosely clamping the other of said workpieces to the otherof said electrodes, applying a potential between said electrodes andmoving said loosely clamped workpiece into contact with said oneworkpiece thereby dis- 1 1 charging said potential through saidworkpieces whereby welding of said pieces is effected.

2. A method of welding in accordance with claim 1 wherein saidworkpieces are of small diameter and including the steps of, prior tomoving said loosely clamped workpiece into contact with said fixedpiece, and discharging said potential, applying a potential to saidelectrodes, moving said loosely clamped workpiece into contact with saidfixed workpiece so as to discharge said potential through saidworkpieces, and removing said loosely clamped workpiece from said fixedworkpiece.

3. A method of welding in accordance with claim 2 including the stepsof, prior to moving said loosely clamped workpiece into contact withsaid fixed workpiece, and discharging said potential; applying apotential to said electrodes, moving said loosely clamped workpiece intocontact with said fixed workpiece so as to discharge said potentialthrough said workpieces, and removing said loosely clamped workpiecefrom said fixed workpiece.

4. A method of welding in accordance with claim 1 including the step ofproviding workpieces of differing metallic compositions.

5. A method of welding in accordance with claim 1 including the step ofproviding workpieces having differing diameters.

6. A method of welding in accordance with claim 1 wherein one of saidworkpieces comprises a single wire and wherein the other of saidworkpieces comprises a plurality of wires, and wherein said clampingstep includes the step of tightly clamping said plurality of wires.

7. A method of welding in accordance with claim 1 wherein saidworkpieces comprise wires and including the steps of providing groovesin said electrodes to receive said wires, and aligning said grooves, andstraightening said one wire as it is clamped and straightening saidloosely engaged wire as it is clamped.

8. A method of welding at least two small diameter wires end to end in acapacitive discharge welding machine having a pair of fixed, spacedelectrode die-holders; comprising the steps of clamping one of saidwires to one of said electrodes, loosely clamping the other of saidwires to the other of said electrodes, applying a potential between saidelectrodes and rapidly propelling said loosely engaged wire into contactwith said one wire thereby discharging said potential through said wireswhereby welding of said wires is effected.

9. A method of Welding in accordance with claim 8 including the steps ofproviding a groove in each of said electrodes to receive said Wires, andaxially aligning said grooves prior to the clamping steps.

10. A method of welding in accordance with claim 9 including the stepsof straightening said one wire as it is clamped.

11. A method of welding in accordance with claim 8 including the stepof, prior to clamping, providing a point on at least one of said wires.

12. Welding apparatus for use in welding small workpieces comprising apair of spaced electrode die-holders, each of said die-holders being ina fixed relation to the other and each having an upstanding leg portionwith workpiece receiving means thereon, clamping means positioned withrespect to said electrodes so as to loosely clamp at least one of saidworkpieces in said receiving means, and a welding pack connecting saidelectrodes and having means to actuate said pack whereby a potential isplaced between said workpieces.

13. Welding apparatus in accordance with claim 12 wherein said workpiecereceiving means comprises means defining a groove and wherein at leastone of said grooves terminates in a recessed portion and said clampingmeans comprises a clamp pivotably mounted with respect to said grooveand positioned with respect thereto so as to wipe against and therebystraighten a workpiece placed in said recessed portion.

14. Welding apparatus in accordance with claim 12 wherein said workpiecereceiving means comprises a groove in the extended terminus of saidupstanding leg portion, and including means to initially adjust one ofsaid electrode die-holders with respect to the other electrodedie-holder so as to permit horizontal and vertical alignment of saidgrooves.

'15. Welding apparatus in accordance with claim 12 wherein saidreceiving means includes a pedestal portion on said terminal portion ofsaid leg and having a groove in said pedestal portion, said groove insaid pedestal having a rearward terminal recession, for receivingtherein said workpiece.

'16. Welding apparatus in accordance with claim 15 wherein at least oneof said clamping means comprises a clamp having a horizontal extensionpivotably secured to its associated leg by adjustment means permittingrotatable movement of said extension and vertical adjustment thereof.

17. Welding apparatus in accordance with claim 12 wherein said weldingpack is a capacitive discharge, direct current welder.

18. Welding apparatus in accordance with claim 12 wherein at least oneof said clamps comprises a yoke having a pair of upstanding legssupporting a clamping bar, said clamping bar alignable with said legportion, said yoke having biasing means mounted with respect to saidelectrode die-holders so as to permit upward biasing thereof, and meansconnecting said yoke to cause said bar to register, as desired, withsaid leg portion.

19. Welding apparatus in accordance with claim 18 wherein said yokeincludes a stern and said means comprises a foot pedal connecting saidstem.

20. Welding apparatus in accordance with claim 19 wherein said weldingpack is a capacitive discharge welder, and wherein said foot pedalincludes a switch connected to said welding pack to thereby place apotential on said workpieces.

21. Welding apparatus in accordance with claim 20 including automaticstriking mechanism having a portion positioned rearwardly of theterminus of said loosely clamped workpiece and adapted to cause saidworkpiece to be propelled toward said fixedly clamped workpiece.

22. Welding apparatus in accordance with claim 21 wherein said strikingmechanism comprises a spring and a latch, said latch engageable withsaid spring to hold said spring in a cocked position and means torelease said latch.

23. An article of manufacture comprising a composite wire including afirst portion formed of a single wire and a second portion contiguous tothe first and including a plurality of separate wire ends, saidplurality of separate wire ends being connected to said single wire by aweld at a common weld point and being connected together in the area ofthe weld point only at the weld point.

24. An article of manufacture in accordance with claim 23 wherein theweld point is the terminal end of said single wire. f

References Cited UNITED STATES PATENTS 1,722,195 7/1929 Bumstead et al219-104 1,908,859 5/1933 ONeill 219-104 X 2,018,380 10/ 1935 Pfeifier219-104 2,363,028 10/1944 Warnke 219-104 X 2,413,043 12/1946 Ganci219-104 X 2,427,727 9/ 1947 Huntley et al 219-104 X 2,604,570 7/1952Aversten 219-158 2,777,046 1/1957 Vang 219-104 2,843,724 7/1958 De Gaetaet al. 2.19-104 X RICHARD M. WOOD, Primary Examiner.

B. A. STEIN, Assistant Examiner.

